Plate fin heat exchanger flexible manifold

ABSTRACT

A flexible manifold adapted for use on a plate-fin heat exchanger core, the flexible manifold including a plurality of individual layers configured to be metallurgically joined to respective ones of a plurality of layers of the plate-fin heat exchanger core, and further including a first end with at least one port adapted to receive or discharge a medium, a second end distal from the first end, adapted to transfer the medium to or from the plurality of individual layers, a plurality of horizontal guide vanes defining the plurality of individual layers, and a plurality vertical members positioned within each of the individual layers. The flexible manifold is configured to be mechanically and thermally compliant, and can be metallurgically joined to the heat exchanger core by brazing or welding.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation in part of U.S. patent applicationSer. No. 15/923,561, entitled “INTEGRAL HEAT EXCHANGER MANIFOLD GUIDEVANES AND SUPPORTS”, filed Mar. 16, 2018, which is hereby incorporatedby reference in its entirety.

BACKGROUND

The present disclosure relates to heat exchangers, and moreparticularly, to a plate-fin heat exchanger manifold design thatimproves the thermal robustness of the plate-fin heat exchanger.

Plate-fin heat exchangers are well known in the aviation arts and inother industries for providing a compact, low-weight, andhighly-effective means of exchanging heat from a hot fluid to a coldfluid. Heat exchangers that operate at elevated temperatures, such asthose in modern aircraft engines, often have short service lives due tohigh steady state and cyclic thermal stresses. Inlet and exit manifoldsare typically pressure vessels that are welded or bolted at only theexterior perimeter to a heat exchanger core or matrix. Pressurerequirements dictate the thickness of these manifolds, usually resultingin a relatively thick header attached to a thin core matrix. Thismismatch in thickness and mass, while acceptable for pressure loads,conflicts with the goal of avoiding geometric, stiffness, mass, andmaterial discontinuities to limit thermal stress.

SUMMARY

A flexible manifold adapted for use on a plate-fin heat exchanger core,the flexible manifold having a number of individual layers, and furtherincluding a first end with at least one port adapted to receive ordischarge a medium, a second end opposite from the first end, adapted totransfer the medium to or from the plurality of individual layers, anumber of horizontal guide vanes defining the number of individuallayers, and a number vertical members positioned within each of theindividual layers. Two adjacent horizontal guide vanes define anindividual layer, the individual layers are configured to bemetallurgically joined to respective ones of the layers of the plate-finheat exchanger core, and the flexible manifold is configured to bemechanically and thermally compliant.

A method of forming a plate-fin heat exchanger having a heat exchangercore and at least one flexible manifold, the method includes forming theheat exchanger core, having a number of individual core layers, andmetallurgically joining each of the individual layers of at least oneflexible manifold to respective ones of the plurality the individualcore layers, thereby metallurgically joining at least one flexiblemanifold to the heat exchanger core.

A plate-fin heat exchanger includes a plate-fin heat exchanger core anda flexible manifold adapted for use on the plate-fin heat exchangercore. The flexible manifold includes a number of individual layers, andfurther including a first end with at least one port adapted to receiveor discharge a medium, a second end opposite from the first end, adaptedto transfer the medium to or from each of the individual layers, anumber of horizontal guide vanes defining the plurality of individuallayers, and a number of vertical members disposed within each of theindividual layers. The individual layers are configured to bemetallurgically joined to respective ones of the layers of the plate-finheat exchanger core, and the flexible manifold is configured to bemechanically and thermally compliant.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a plate-fin heat exchanger core with ahot layer inlet and outlet flexible manifolds.

FIG. 1B is a side view of the plate-fin heat exchanger core with the hotlayer inlet and outlet flexible manifolds shown in FIG. 1A.

FIG. 2 is a perspective view of a second embodiment of a flexiblemanifold.

FIG. 3A is a quarter cut-away perspective view of the flexible manifoldshown in FIG. 2 .

FIG. 3B is an end view of a portion of an individual layer of theflexible manifold shown in FIG. 3A.

FIG. 4 is a top cross-sectional view of a layer of the flexible manifoldshown in FIG. 2 .

FIG. 5A is a side view of a portion of the plate-fin heat exchanger corewith a first hot manifold.

FIG. 5B is a cross-sectional end view of the heat exchanger core of FIG.5A.

FIG. 5C is an enlarged section of the heat exchanger core of FIG. 5B.

FIG. 6 is a side view of a portion of a second embodiment of theplate-fin heat exchanger core with a first hot manifold.

FIG. 7 is a flow chart depicting a process steps for brazing theflexible manifolds to the heat exchanger core.

FIG. 8 is a flow chart depicting a process steps for welding theflexible manifolds to the heat exchanger core.

DETAILED DESCRIPTION

FIG. 1A is a perspective view of a plate-fin heat exchanger core showingthe hot layer inlet and outlet manifolds. Shown in FIG. 1A are heatexchanger 10, heat exchanger core 12, first hot manifold 14, second hotmanifold 16, hot inlet 40, and hot outlet 42. Heat exchanger 10 includesheat exchanger core 12, where heat can be transferred from a hot medium(not shown) to a cold medium (not shown), while separating the hotmedium from the cold medium. Accordingly, heat exchanger 10 includes ahot circuit (not shown) and a cold circuit (not shown). The hot and coldmediums can be a fluid, either or both being a liquid, gas, and/or amixture of liquid and gas. The hot and/or cold mediums can change phasein or near heat exchanger 10. The hot and/or cold mediums can entrainparticles. As used in this disclosure, the hot and/or cold mediums canbe referred to as fluids.

The hot medium can be called a first medium, and the cold medium can becalled a second medium. Accordingly, the hot circuit can be called afirst circuit, and the cold circuit can be called a second circuit. Thehot medium enters first hot manifold 14 at hot inlet 40, flows throughheat exchanger core 12, and exits through second hot manifold 16 at hotoutlet 42. Heat exchanger 10 can also include a first and second coldmanifold (not shown) for directing the cold circuit. Heat exchanger 10depicted in FIG. 1A is a cross-flow heat exchanger, because flow throughthe hot flow circuit is generally across flow through the cold flowcircuit (i.e., the direction of hot flow through the heat exchanger coreis generally perpendicular to the direction of cold flow through theheat exchanger core). The flow configuration can be different in otherembodiments. Moreover, in other embodiments, more than one hot inlet 40and/or hot outlet 42 can exist.

FIG. 1B is a side view of the plate-fin heat exchanger core of FIG. 1A.Shown is FIG. 1B are heat exchanger 10, heat exchanger core 12, firsthot manifold 14, second hot manifold 16, bottom end sheet 20, hotclosure bars 22, parting sheets 24, cold fins 26, cold closure bars 28,top end sheet 32, hot layers 34, individual layers 36, cold layers 38,hot inlet 40, and hot outlet 42. As described above with respect to FIG.1A, the hot medium (not shown) enters first hot manifold 14 at hot inlet40. The hot medium is directed via individual layers 36 into heatexchanger core hot layers 34, then recombines in second hot manifold 16and exits via hot outlet 42. Alternating hot layers 34 and cold layers38 are sandwiched between bottom end sheet 20 and top end sheet 32. Hotfins (not shown) channel the flow of the hot medium with boundariesdefined by hot closure bars 22 on either side of each hot layer, andparting sheets 24 on the top and bottom of each layer. Similarly, coldfins 26 channel the flow of the cold medium with boundaries defined bycold closure bars 28 on either side of each cold layer, and partingsheets 24 on the top and bottom of each layer. In the illustratedembodiment, ten hot layers and nine cold layers are used. In otherembodiments, there can be practically any number of hot layers and/orcold layers. First and second hot manifolds 14, 16 can be calledflexible manifolds because they are thermally and mechanicallycompliant.

FIG. 2 is a perspective view of a second embodiment of the flexiblemanifold. FIG. 3A is a quarter cut-away perspective view of the flexiblemanifold of FIG. 2 . FIG. 3B is an end view of a portion of anindividual layer of the flexible manifold shown in FIG. 3A. Shown inFIGS. 2 and 3A-3B are flexible manifold 114, housing 115, port 124,first end 126, second end 128, horizontal guide vanes 130, verticalguide vanes 132, individual layers 136, discrete manifold flow passages140, side wall second end region 154, and floor second end region 156.Accordingly, as used herein, floor second end region 156 refers to boththe lower and upper horizontal sections of each individual layer 136,and can also be referred to as “floor”. Moreover, as used herein, theterms “vertical” and “horizontal” are relative to a standard uprightorientation of the heat exchanger, and they do not necessarily implythese guide vanes have specific orientations relative to gravity or theplacement and/or orientation of the heat exchanger. Moreover, theseterms do not necessarily require, unless specifically stated, that thevanes are exactly perpendicular to one another at some or all points.Accordingly, horizontal guide vanes 130 can be called first guide vanes,and vertical guide vanes 132 can be called second guide vanes.

A plurality of horizontal guide vanes 130 extending at least part of adistance from the first end 126 to the second end 128 of flexiblemanifold 114, or vice versa, define individual layers 136 for at leastone medium (e.g., the hot medium in FIGS. 1A-1B). Together withhorizontal guide vanes 130, a plurality of vertical guide vanes 132,formed at a nonzero angle to horizontal guide vanes 130, can divide onesof the individual layers 136 into a plurality of first discrete manifoldflow passages 140 extending at least part of a distance from the firstend 126 to the second end 128 of flexible manifold 114, or vice versa.In some embodiments, vertical guide vanes 132 can make an angle that isnear 90 deg. to horizontal guide vanes 130. Direction of flow woulddepend on whether flexible manifold 114 is serving as an inlet manifoldor an outlet manifold.

Individual layers 136 of flexible manifold 114 can be formed as gradualtransitions (i.e., continuous, homogeneous transitions) from first end126 to second end 128 to reduce or eliminate discontinuities thatotherwise in conventional designs can cause high stress to the heatexchanger core (not shown), which can lead to an abbreviated servicelife. Rather, in the present design, the plurality of horizontal vanes130 and thus individual layers 136 are cantilevered and flexible toallow for elastic deformation from media flowing through the manifoldpassages. As shown, first end 126 can include an opening or port 124 ofsize A (sized for coupling to a duct, pipe, or the like to receive thefirst medium 120) that is smaller than a size B of second end 128 at amanifold/core interface (e.g., heat exchanger core 12 in FIGS. 1A-1B).Size A can be a diameter of port 124. Size B can be a height of anopening at second end 128. Size B can also correspond to the cumulativearea of the opening at second end 128. Depicted in FIG. 3B is a portionof individual layer 136 as viewed from second end 128 showing side wallsecond end region 154 and floor second end region 156. With reference toindividual layers 136, side wall second end region 154 can be referredto as the sidewalls, and floor second end regions 156 can be referred toas the floors. In the illustrated embodiment, “floor” refers to both theupper and lower floor second end regions 156 of individual layer 136.Side wall second end region 154 has thickness E, and floor second endregion 156 has thickness F, as shown in FIG. 3B.

Flexible manifold 114 can be formed by additive manufacturing, hybridadditive subtractive manufacturing, subtractive manufacturing, and/orcasting, for example. Embodiments of flexible manifolds 114 describedherein can leverage additive manufacturing or any other manufacturingmethod or methods (e.g., casting) that allows one to constructcontinuous, homogeneous transitions between the heat exchanger core 114and one or more flexible manifolds 113. Additive manufacturing is alsouseful in building and tailoring vertical guide vanes 132 withinflexible manifolds 114. As horizontal guide vanes 130 reducediscontinuities in material properties and thermal expansion betweenflexible manifold 114 and heat exchanger core 12, vertical guide vanes132 provide stiffness and support to withstand the pressure of medium(s)flowing through flexible manifold 114 (where welds or bolted flanges arerequired in conventional heat exchangers). Accordingly, a method of thepresent disclosure includes forming heat exchanger core 12 for heatexchanger 10 and additively manufacturing a first flexible manifold 114for heat exchanger 10. Forming a first flexible manifold 114 includesadditively building housing 115 for first flexible manifold 114. Withinhousing 115, a plurality of horizontal guide vanes 130 are additivelybuilt, defining individual layers 136 for the first medium. A pluralityof vertical guide vanes 132 can also be additively built, dividing onesof individual layers 136 into a plurality of discrete manifold flowpassages 140.

In an exemplary embodiment, powder bed fusion can be used as an additivemanufacturing process to fabricate flexible manifold 114 from metallicmaterials. Non-limiting examples of metallic materials that can be usedinclude nickel, aluminum, titanium, copper, iron, cobalt, and all alloysthat include these various metals. In some embodiments, various alloysof INCONEL™ can be used to fabricate flexible manifold 114, with Inconel625 and Inconel 718 being two exemplary alloy formulations. In otherembodiments, HAYNES™ 282 can be used in fabricating flexible manifold114. In yet other embodiments, alloys of aluminum can be used infabricating to flexible manifold 114. For example, an alloy of aluminumknown as AlSi10Mg can be used in fabricating flexible manifold 114. Allmaterials that include metals, metal oxides, and alloys thereof infabricating flexible manifold 114 are within the scope of the presentdisclosure.

FIG. 4 is a top cross-sectional view taken at cut-line 4-4 of layer 136of flexible manifold 114 shown in FIG. 3 . Shown in FIG. 4 are first end126, second end 128, horizontal guide vane 130, vertical guide vanes132, individual layer 136, discrete manifold flow passage 140, side wall150, side wall first end region 152, and side wall second end region154. The medium flowing through individual layer 136 is contained byhorizontal guide vanes 130 which form the top and bottom pressureboundaries of individual layer 136, and by side walls 150 which form theside pressure boundaries of individual layer 136. Vertical guide vanes132 direct the flow through individual layer 136, thereby formingdiscrete manifold flow passages 140. Each side wall 150 has side wallfirst end region 152 and side wall second end region 154. The thicknessof side wall 150 generally tapers from a greater thickness at side wallfirst end region 152 (corresponding to first end 126) to a smallerthickness at side wall second end region 154 (corresponding to secondend 128). In the vicinity of second end 128, side wall 150 has secondend side wall thickness E as shown in FIG. 4 . Vertical guide vanes 132connect from lower horizontal guide vane 130 to the upper guide vane 130in each individual layer 136, thereby helping provide structural supportfor individual layers 136. In a particular embodiment, flexible manifold114 can be used in an application where the medium has a pressure ashigh as 1,000 psi (6,895 KPa). Accordingly, vertical guide vanes 132 canassist in limiting or preventing individual layers 136 from deformingunder the working pressure of the medium, thereby enhancing themechanical compliancy of flexible manifold 114. Vertical guide vanes 132can also be referred to as vertical members.

In the illustrated embodiment, second end side wall thickness E can beequal to the thickness of hot closure bars 22 as shown in FIG. 1B. Inthese embodiments, side walls 150 are metallurgically joined at sidewall second end region 154 to hot closure bars 22, thereby partiallyjoining flexible manifold 114 (shown in FIGS. 2-3 ) to a heat exchangercore. Accordingly, in these particular embodiments, the mechanicaland/or thermal flexibility of flexible manifold 114 can be enhanced bythe selection of thickness E of sidewall second end region 154 andthickness E of hot closure bar 22. In the illustrated embodiment, hotclosure bars 22 can have a thickness that is equal to second end sidewall thickness E. In other embodiments, hot closure bars 22 can have athickness that is either greater than or less than second end side wallthickness E.

In the embodiment illustrated in FIG. 4 , flexible manifold 114 can bean inlet manifold, whereby the flow of a medium can enter individuallayer at first end 126 and exit at second end 128 where it can enter aheat exchanger core as described with regard to FIGS. 2-3 . In anotherembodiment, flexible manifold 114 can be an outlet manifold, with mediumflow occurring in the opposite direction as described.

FIG. 5A is a side view of a portion of plate-fin heat exchanger core 12with first hot manifold 14 as shown in FIG. 1B. FIG. 5B is across-sectional end view of the heat exchanger core of FIG. 5A, and FIG.5C is an enlarged section of the heat exchanger core of FIG. 5B. Shownin FIGS. 5A-5C are heat exchanger core 12, first hot manifold 14, bottomend sheet 20, hot closure bars 22, parting sheets 24, cold fins 26, topend sheet 32, hot layers 34, individual layers 36, cold layers 38, hotinlet 40, and metallurgical bonds 50. The description of FIGS. 5A-5C aresubstantially the same as that provided above with regard to FIG. 1B.Additionally shown in FIG. 5A are metallurgical bonds 50 joining eachindividual layer 36 to the respective hot closure bars 22 and partingsheets 24 of heat exchanger core 12. Similarly, metallurgical bonds 50join each individual layer 36 of hot outlet (not shown) to therespective hot closure bars 22 and parting sheets 24 of heat exchangercore 12. Referring to FIG. 5C, each hot layer 34 includes hot fin 30,hot closure bars 22 on the left and right, and parting sheets 24 on thetop and bottom. Similarly, each cold layer 38 includes cold fins 26,cold closure bars 28 on the front and back (not shown), and partingsheets 24 on the top and bottom. Generally, a particular parting sheet24 is shared by an adjacent hot layer 34 and cold layer 38. Hot closurebar 22 has thickness E, and parting sheet 24 has thickness F. Eachindividual layer 36 includes side walls 150 and individual layer floors(not shown in FIG. 5A), with the side walls being the outer verticalportions of individual layer 36 and the individual layer floors beingthe upper and lower horizontal portions of individual layers 36.Accordingly, as used herein, “floor” refers to both the lower and upperhorizontal sections of each individual layer 36. Therefore,metallurgical bonds 50 exist between the side walls and closure bars 22,and between the individual layer floors and parting sheets 24 on firsthot manifold 14 and on the second hot manifold (not shown in FIG. 5A).

In the illustrated embodiment, floor thickness F (as shown in FIG. 3B)can be equal to thickness F of parting sheet 24 (as shown in FIG. 5C).In these embodiments, individual floors are metallurgically joined toparting sheets 24, thereby partially joining flexible manifold 114 toheat exchanger core 12. Accordingly, by providing the floor thickness Fequal to thickness F of parting sheet 24, the mechanical and/or thermalflexibility of flexible manifold 114 can be enhanced. This can bereferred to as being mechanically and thermally compliant, in whichflexible manifold 114 is able to withstand temperature and/or pressurechanges and/or transients. In some embodiments, the floor thickness canbe greater than or less than the thickness of parting sheet 24, whichstill contributing to the mechanical and/or thermal compliancy offlexible manifold 114.

Metallurgical bonds 50 can be created by one of several metal bondingprocesses, with non-limiting examples including brazing and welding. Inthe embodiment illustrated in FIG. 5A, metallurgical bonds 50 are formedas butt joints, whereby each hot layer 34 abuts each correspondingindividual layer 36. In the illustrated embodiment of the butt jointshown in FIG. 5A, welding can be used to join each hot layer 34 to acorresponding individual layer 36. Exemplary welding methods that can beused include electron-beam welding and laser welding, and these will bedescribed in more detail in FIG. 8 . All other forms of welding arewithin the scope of the present disclosure. In other embodiments,metallurgical bonds 50 can be formed by brazing. The foregoingdescription pertains to the joining of hot manifolds to heat exchangercore 12. In a typical embodiment, cold manifolds (not shown) can bejoined to heat exchanger core 12 by using a similar metal bondingprocess.

FIG. 6 is an enlarged side view of a second embodiment of plate-fin heatexchanger core 212 with first hot manifold 214. Shown in FIG. 6 are heatexchanger core 212, first hot manifold 214, bottom end sheet 220, hotclosure bars 222, parting sheets 224, cold fins 226, cold closure bars228, top end sheet 232, hot layers 234, individual layers 236, coldlayers 238, hot inlet 240, and metallurgical bonds 250. The descriptionof FIG. 6 is substantially the same as that provided above with regardto FIG. 5A, with the exception that metallurgical bonds 250 are formedas lap joints, whereby each hot layer 234 partially enters eachcorresponding individual layer 236. In the illustrated embodiment of thelap joint shown in FIG. 6 , brazing can be used to join each hot layer234 to a corresponding individual layer 236. In an exemplary lap jointbrazing process, the manifold-facing portions of each hot layer 234 arecoated with a brazing material. During the brazing process, the coatedbrazing material on each hot layer 234 melts, forming a metallurgicalbond with each corresponding individual layer 236. The brazing processthat forms metallurgical bonds 250 will be described in more detail inFIG. 7 . In other embodiments, metallurgical bonds 250 can be formed bywelding. The foregoing description pertains to the joining of first hotmanifold 214 and a second hot manifold (not shown) to heat exchangercore 212. In a typical embodiment, cold manifolds (not shown) can bejoined to heat exchanger core 212 by using a similar metal bondingprocess.

FIG. 7 is a flow chart depicting exemplary process steps for brazingflexible manifolds (i.e., first hot manifold 214, second hot manifold,first and second cold manifolds) to heat exchanger core 212 as shown inFIG. 6 . Shown in FIG. 7 are the following process steps: stack corecomponents step 702, clamp core components step 704, clamp flexiblemanifold step 706, brazing operation step 708, and remove heat exchangerstep 710. In the process shown in FIG. 7 , flexible manifolds are brazedto heat exchanger core 212 as a bulk process occurring during thebrazing of heat exchanger core 212.

Brazing is a method that can be used to metallurgically join one or moreflexible manifolds to a heat exchanger core. The process depicted inFIG. 7 can be used to form metallurgical bonds 250 as were shown in FIG.6 . In the illustrated embodiment, assembly of heat exchanger corebegins with stack core components step 702 in which the variouscomponents that will become the heat exchanger core are stacked togetherin a brazing fixture. These various components can be coated with abrazing material which, after melting, forms metallurgical bonds betweenthe various components.

Next, in clamp core components step 704, a preload force is applied tothe heat exchanger core components which are then clamped into position.For example, the preload force can partially compress the various hotand cold fins to establish the proper dimensions of the completed heatexchanger core while also ensuring proper contact exists between thevarious hot and cold fins and the bottom end sheet, parting sheets, andtop end sheet. Next, in clamp flexible manifold step 706, the flexiblemanifolds that comprise the finished heat exchanger are positioned andclamped into position against the heat exchanger core components. Therecan be overlapping engagement of hot layers 234 and individual layers236, in which each hot layer 234 matingly engages with a respectiveindividual layer 236 as shown in FIG. 6 , thereby forming a lap joint.

The foregoing description of FIGS. 1A-1B focused primarily on the hotcircuit of heat exchanger 10. In the embodiment shown in FIGS. 1A-1B,the cold circuit also includes cold manifolds (not shown) that aresubstantially similar to hot manifolds 216. Accordingly, clamp flexiblemanifold step 706 can include positioning and clamping flexiblemanifolds for the hot and cold circuits (i.e., first and second hotmanifolds, first and second cold manifolds).

Next, the heat exchanger core components and flexible manifolds aremetallurgically joined in perform brazing operation step 708. In anexemplary manufacturing process, the brazing fixture that holds the heatexchanger core components and flexible manifolds is placed into abrazing furnace. Brazing furnaces are known to those who are skilled inthe plate-fin heat exchanger arts. An exemplary brazing process caninclude evacuating the air from the brazing furnace so that the stackedheat exchanger core components are in a vacuum. Next, the temperature inthe brazing furnace is increased to at least the brazing melttemperature and held for a period of time to allow the brazing materialto melt and flow. The brazing furnace temperature is then lowered,thereby allowing the brazing material to solidify, and the brazingfurnace can be backfilled by an inert gas. An annealing cycle can alsobe performed in some embodiments.

The final step shown in FIG. 7 is remove heat exchanger step 710, inwhich the metallurgically-joined heat exchanger core 212 and theflexible manifolds (i.e., the heat exchanger) is removed from thebrazing furnace. This step can include removing the heat exchanger fromthe brazing fixture, after which additional process steps can beperformed. For example, in some embodiments, inspection and testing ofthe heat exchanger is performed to assure the completeness of themetallurgical joining process. For the purpose of this discussion, ametallurgically-joined heat exchanger core and one or more flexiblemanifolds can be referred to as a heat exchanger without regard to thecompleteness of the heat exchanger. It is to be recognized that a fullycomplete heat exchanger will include a heat exchanger coremetallutgically-joined to all hot and cold manifolds for which the heatexchanger is designed.

In the embodiment illustrated in FIG. 7 , perform brazing operation step708 included brazing the heat exchanger core components and the flexiblemanifolds in one step. In another embodiment, the heat exchanger corecan be brazed in a first brazing step, and then the flexible manifoldscan be metallurgically joined to the heat exchanger core in a secondbrazing step.

FIG. 8 is a flow chart depicting exemplary process steps for welding theflexible manifolds to the heat exchanger core. Welding is a method thatcan be used to metallurgically join one or more flexible manifolds to aheat exchanger core. As described earlier with regard to FIG. 5A, allwelding processes are within the scope of the present application.Non-limiting exemplary welding processes are electron beam welding andlaser welding. The flow chart depicted in FIG. 8 follows similar processsteps to those depicted in FIG. 7 , with the significant differencebeing that welding is used to form metallurgical joints 50 as shown inFIG. 5A. Shown in FIG. 8 are the following process steps: brazingoperation step 802, position in welding fixture step 804, clamp flexiblemanifold step 806, welding operation step 808, and remove heat exchangerstep 810. In the process shown in FIG. 8 , the various components thatwill become the heat exchanger core are stacked together in a brazingfixture. These various components can be coated with a brazing materialwhich, after melting, forms metallurgical bonds between the variouscomponents. A preload force can be applied to the heat exchanger corecomponents which are then clamped into position, similar to the processdescribed above with regard to FIG. 7 . The heat exchanger corecomponents are then placed in a brazing furnace, and the brazingoperation is performed. In the illustrated embodiment, the brazing ofthe heat exchanger core can be substantially similar to the processdescribed above in regard to FIG. 7 , with the exception that the heatexchanger core is brazed without the flexible manifolds. Next, afterremoving the brazed heat exchanger core from the brazing furnace,position in welding fixture step 804 is performed to position the heatexchanger core in a fixture that will accommodate a welding operation.Next, clamp flexible manifold step 806 can include positioning andclamping flexible manifolds for the hot and cold circuits (i.e., firstand second hot manifolds, and also first and second cold manifolds)against the heat exchanger core. In some embodiments, a machining stepcan be performed prior to clamp flexible manifold step 806 to assist inproviding a proper mechanical fit and/or dimensional tolerances betweenheat exchanger core 212 and the flexible manifolds.

Next, the flexible manifolds are metallurgically joined to the heatexchanger core in welding operation step 808. Electron beam welding(EBW) and laser welding are fusion metallurgical joining processes thatcan produce a weld zone joining each of the individual layers of arespective flexible manifold to the corresponding layers of the heatexchanger core, with EBW and laser welding being known to those skilledin the metallurgical joining arts. In a first embodiment, EBW can beused as a welding process by which electrons are accelerated to a highenergy and directed as a beam to the region to be welded whereby metalfusion occurs. In a typical embodiment, EBW can be performed in a vacuumor near-vacuum. In other embodiments, EBW can be performed in an inertatmosphere. Argon gas is an example of an inert atmosphere that can beused in the vicinity of the weld. In yet other embodiments, EBW canoccur in air, in a rarefied atmosphere, or in a partial vacuum.

In an exemplary embodiment, a single electron beam is progressivelydirected at all areas to be welded in welding operation step 808. Thatis, each individual layer of each flexible manifold is sequentiallywelded to each corresponding layer of a heat exchanger core. In anotherembodiment, multiple electron beams can be used, either acting onmultiple individual layers and/or multiple regions of an individuallayer simultaneously to each other. One advantage of using multipleelectron beams can be to shorten the overall time taken to completewelding operation step 808.

In a second embodiment of welding operation step 808, a laser can beused to provide a high-power laser beam that produces the metallurgicalbond. A laser beam can be directed at the region to be welded, wherebymetal fusion occurs. The description of laser welding is similar to theforegoing description of EBW with regard to the use of a single ormultiple laser beams as well as the atmosphere or vacuum of the weldenvironment.

In the exemplary embodiment depicted in FIG. 8 , all flexible manifoldscan be joined to the heat exchanger core in welding operation step 808,with the total number of flexible manifolds being determined by theparticular design of a heat exchanger. In other embodiments, one or moreflexible manifolds can be joined to the heat exchanger core in weldingoperation step 808.

Next, in remove heat exchanger step 810, the heat exchanger is removedfrom the welding chamber and from the welding fixture that held theflexible manifolds in position against the heat exchanger core.Additional process steps can be performed. For example, in someembodiments, inspection and testing of the heat exchanger is performedto assure the completeness of the metallurgical joining process.

In some embodiments, multiple flexible manifolds can be joined to theheat exchanger core at one time in welding operation step 808. In otherembodiments, only a single flexible manifold can be joined to exchangercore in welding operation step 808. In these other embodiments, processsteps will be repeated in order to complete the welding of all flexiblemanifolds to a heat exchanger core. For example, in an embodiment wherefewer than all flexible manifolds are welded to a heat exchanger core inwelding operation step 808, then clamp flexible manifold step 806,welding operation step 808, and remove heat exchanger step 810 can berepeated as necessary.

As used in this disclosure, the terms “high-energy” and “high-power” areused to describe an electron beam and/or laser beam by implying that thebeam is capable of fusing metal during welding operation step 808. It isto be appreciated that power is a rate of delivering energy, and thatthe energy level and/or power of the particular beam is configured toproduce the metallurgical joining of a flexible manifold to a heatexchanger core. In a particular embodiment several factors can beconsidered in the selection of the power level of the welding beamincluding, for example, the energy level of the electrons or thewavelength of the laser.

Welding processes other than EBW and laser welding are within the scopeof the present disclosure. For example, metal inert gas (MIG) andtungsten inert gas (TIG) are known to those who are skilled in themetallurgical joining arts. Welding operation step 808 can include MIGor TIG welding that is configured to accommodate the welding of aflexible manifold to a heat exchanger core. Other welding processes arewithin the scope of the present disclosure. Moreover, multiple types ofwelding processes can be used in the metallurgical joining of flexiblemanifolds to a heat exchanger core in a particular embodiment, withnon-limiting examples being a combination of EBW and laser welding.

The foregoing descriptions include the metallurgical joining of flexiblemanifolds to a heat exchanger core by using either brazing or welding,as depicted in FIGS. 7 and 8 , respectively. In the exemplaryembodiments described in the present disclosure, metallurgical bonds 50shown in FIG. 5A were formed by welding, resulting in bonds that can bereferred to as a butt joints, and metallurgical bonds 250 shown in FIG.6 were formed by brazing, resulting in joints that can be referred to asa lap joints. It is to be appreciated that in other embodiments a buttjoint can be formed by any metallurgical joining process (includingbrazing), and a lap joint can be formed by any metallurgical joiningprocess (including welding). Moreover, utilizing multiple metallurgicaljoining processes for a particular heat exchanger is within the scope ofthe present disclosure. In an exemplary heat exchanger, the hot layersand cold layers can be of different sizes. Therefore, the individuallayers of the hot flexible manifolds can be a different size from theindividual layers of the cold flexible manifolds. In this exemplaryembodiment, brazing can be used to join one set of flexible manifolds tothe heat exchanger core, and welding can be used to join the other setof flexible manifolds to the heat exchanger core.

Discussion of Possible Embodiments

The following are non-exclusive descriptions of possible embodiments ofthe present invention.

A flexible manifold adapted for use on a plate-fin heat exchanger core,the flexible manifold comprising a plurality of individual layers, andfurther comprising: a first end with at least one port adapted toreceive or discharge a medium; a second end distal from the first end,adapted to transfer the medium to or from the plurality of individuallayers; a plurality of horizontal guide vanes defining the plurality ofindividual layers; and a plurality vertical members disposed within eachof the individual layers; wherein: two adjacent horizontal guide vanesdefine an individual layer; the plurality of individual layers areconfigured to be metallurgically joined to respective ones of aplurality of layers of the plate-fin heat exchanger core; and theflexible manifold is configured to be mechanically and thermallycompliant.

The flexible manifold of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingfeatures, configurations and/or additional components:

A further embodiment of the foregoing flexible manifold, each of theplurality of layers of the plate-fin heat exchanger core including twoparting sheets, each defining a parting sheet thickness, and two closurebars, each defining a closure bar thickness, wherein each of theplurality of individual layers includes a side wall defining a side wallthickness and a floor defining a floor thickness.

A further embodiment of the foregoing flexible manifold, wherein theside wall thickness is equal to the closure bar thickness.

A further embodiment of the foregoing flexible manifold, wherein thefloor thickness is equal to the parting sheet thickness.

A further embodiment of the foregoing flexible manifold, comprising oneor more of nickel, aluminum, titanium, copper, iron, cobalt, and alloysthereof.

A further embodiment of the foregoing flexible manifold, comprisingInconel 625, Inconel 718, Haynes 282, or AlSi10Mg.

A further embodiment of the foregoing flexible manifold, wherein each ofthe individual core layers is configured to matingly join respectiveones of the plurality the individual layers, thereby forming a lapjoint.

A further embodiment of the foregoing flexible manifold, wherein thevertical members comprise vertical guide vanes dividing each of theplurality of individual layers into a plurality of discrete manifoldflow passages extending at least part of a distance from the first endto the second end of the flexible manifold.

A further embodiment of the foregoing flexible manifold, furthercomprising a plate-fin heat exchanger.

A method of forming a plate-fin heat exchanger having a heat exchangercore and at least one flexible manifold, the method comprising: formingthe heat exchanger core, comprising a plurality of individual corelayers; and metallurgically joining each of a plurality of individuallayers of the at least one flexible manifold to respective ones of theplurality the individual core layers, thereby metallurgically joiningthe at least one flexible manifold to the heat exchanger core.

The method of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingfeatures, configurations and/or additional components:

A further embodiment of the foregoing method, wherein themetallurgically joining comprises brazing.

A further embodiment of the foregoing method, wherein each of theindividual core layers is configured to matingly join a respective oneof the plurality the individual layers, thereby forming a lap joint.

A further embodiment of the foregoing method, wherein the brazingcomprises bulk brazing, thereby brazing the heat exchanger core.

A further embodiment of the foregoing method, wherein the bulk brazingcomprises the steps of: (a) positioning one or more flexible manifoldsin contact with the heat exchanger core in a brazing furnace; (b)raising a temperature in the brazing furnace to at least a melting pointof a brazing material; and (c) lowering the temperature in the brazingfurnace to below the melting point of a brazing material.

A further embodiment of the foregoing method, wherein themetallurgically joining comprises welding.

A further embodiment of the foregoing method, wherein the weldingcomprises electron beam welding or laser welding.

A further embodiment of the foregoing method, wherein the at least oneflexible manifold is produced by at least one of additive manufacturing,hybrid additive subtractive manufacturing, subtractive manufacturing,and casting.

A further embodiment of the foregoing method, wherein the at least oneflexible manifold comprises Inconel 625, Inconel 718, Haynes 282, orAlSi10Mg.

A further embodiment of the foregoing method, further comprisingadditively manufacturing the at least one flexible manifold for the heatexchanger, including the steps of: additively building a housing for thefirst flexible manifold, within the housing, additively building aplurality of horizontal guide vanes defining the individual layers forat least a first medium, and additively building a plurality of verticalmembers within each of the individual layers.

A plate-fin heat exchanger, comprising: a plate-fin heat exchanger core;and a flexible manifold adapted for use on the plate-fin heat exchangercore, the flexible manifold comprising a plurality of individual layers,and further comprising: a first end with at least one port adapted toreceive or discharge a medium; a second end distal from the first end,adapted to transfer the medium to or from the plurality of individuallayers; a plurality of horizontal guide vanes defining the plurality ofindividual layers; and a plurality vertical members disposed within eachof the individual layers; wherein: the plurality of individual layersare configured to be metallurgically joined to respective ones of aplurality of layers of the plate-fin heat exchanger core; and theflexible manifold is configured to be mechanically and thermallycompliant.

While the invention has been described with reference to an exemplaryembodiment(s), it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment(s) disclosed, but that theinvention will include all embodiments falling within the scope of theappended claims.

The invention claimed is:
 1. A flexible manifold adapted for connection to a plate-fin heat exchanger core, the flexible manifold comprising: a first end with at least one port adapted to receive or discharge a medium; a second end distal from the first end, adapted to transfer the medium to or from the plate-fin heat exchanger core, wherein the second end comprises a plurality of openings; a plurality of individual layers extending between the first end and the second end; a plurality of horizontal guide vanes defining the plurality of individual layers; a plurality of manifold flow passages disposed within each layer of the plurality of individual layers and extending from the second end toward the first end; a plurality of gaps extending completely through the flexible manifold and spacing each layer of the plurality of layers apart from one another such that each layer cantilevers toward the second end; and a plurality vertical members disposed within the plurality of individual layers; wherein: each layer of the plurality of individual layers is defined by two adjacent horizontal guide vanes of the plurality of horizontal guide vanes and is configured to be metallurgically joined to a respective core layer of the plate-fin heat exchanger core at an opening of the plurality of openings and form a lap joint with the respective core layer; and the two adjacent horizontal guide vanes are cantilevered with support proximate the first end, unsupported overhang extending towards the second end, and flexible to allow for elastic deformation.
 2. The flexible manifold of claim 1, wherein the respective core layer of the plate-fin heat exchanger core comprises a parting sheet comprising a parting sheet thickness; and two closure bars, wherein each of the two closure bars comprises a closure bar thickness.
 3. The flexible manifold of claim 2, wherein said each layer of the plurality of individual layers includes a side wall, defining a side wall thickness, and a floor defining a floor thickness.
 4. The flexible manifold of claim 3, wherein the floor thickness is equal to the parting sheet thickness.
 5. The flexible manifold of claim 1, comprising one or more of nickel, aluminum, titanium, copper, iron, cobalt, and alloys thereof.
 6. The flexible manifold of claim 5, comprising Inconel 625, Inconel 718, Haynes 282, or AlSi10Mg.
 7. The flexible manifold of claim 1, wherein the vertical members comprise vertical guide vanes dividing each of the plurality of individual layers into a plurality of discrete manifold flow passages extending at least part of a distance from the first end to the second end of the flexible manifold.
 8. A plate-fin heat exchanger, comprising at least one of the flexible manifolds of claim
 1. 9. A plate-fin heat exchanger, comprising: a plate-fin heat exchanger core; and a flexible manifold adapted for use on the plate-fin heat exchanger core, the flexible manifold comprising a plurality of individual layers, and further comprising: a first end with at least one port adapted to receive or discharge a medium; a second end distal from the first end, adapted to transfer the medium to or from the plurality of individual layers, wherein the second end comprises a plurality of openings; a plurality of horizontal guide vanes defining the plurality of individual layers; a plurality of vertical members disposed within each layer of the plurality of individual layers; a plurality of manifold flow passages disposed within each layer of the plurality of individual layers and extending from the second end toward the first end; and a plurality of gaps extending completely through the flexible manifold and spacing each layer of the plurality of individual layers apart from one another as each layer extends toward the second end; wherein: the plurality of individual layers are metallurgically joined at the second end to respective ones of a plurality of layers of the plate-fin heat exchanger core at the plurality of openings with a lap joint.
 10. The flexible manifold of claim 3, wherein the side wall thickness is equal to the closure bar thickness. 